Quality-control mechanism found in bacteria

Like quality-control managers in factories, bacteria possess built-in machinery that track the shape and quality of proteins trying to pass through their cytoplasmic membranes, Cornell biomolecular engineers have shown.

This quality-control mechanism is found in the machinery of the twin-arginine translocation (TAT) pathway, which is a protein export pathway in plants, bacteria and archaea (single-celled microorganisms). The transport of proteins across cellular membranes is a basic life process and understanding how the TAT pathway works could lend insight into, for example, how bacteria become resistant to antibiotics. The discovery is a milestone in a 10-plus year study of the TAT pathway led by Matthew DeLisa, associate professor of chemical and biomolecular engineering, and is detailed in Proceedings of the National Academy of Sciences, July 30.

"Our first paper on this topic [PNAS, May 13, 2003] suggested that, given the fact that only folded proteins can go through this system, perhaps a quality-control mechanism was embedded in the machinery itself," DeLisa said. "That idea turned out to be controversial, but this most recent paper, we think, reopens that possibility.